1. Field of the Invention
The present invention generally relates to a structure to open and close a cover with respect to a main body, an electronic device including the structure, and an image forming apparatus such as a copier, a printer, a facsimile machine, etc., that includes the structure.
2. Discussion of the Background Art
Cover units to open and close a cover of an opening formed in a main body using a push latch device are widely used in electronic devices such as image forming apparatuses, in addition to various cabinets such as television cabinets. Generally, one end of the cover is rotatably hinged to the main body with a shaft, and an engagement portion is provided in the opposite end of the cover. The engagement portion is engaged and disengaged from the push latch device when pressed, and thus the cover is locked to and unlocked from the main body.
In certain known cover units, the cover is locked when pressed while being rotated from an open position to a close position and unlocked when the closed cover is pressed. In this type of cover units, although users can open and close the cover easily, a certain amount of clearance should be kept between the cover and the main body to allow the cover to move when the engagement between the cover and the latch of the push latch unit is released. Therefore, where the cover is to be pushed to unlocked the cover is not precisely limited to the area around the engagement portion (e.g., lock portion). Consequently, if this cover unit is used in electronic devices, it can happen that the cover is accidentally unlocked when the user contacts the cover unintentionally, and accordingly the electronic device stops even if an operation is in progress.
Other certain known cover units use a push latch unit that is attached to the main body and includes a pushing rod movable to and away from the cover, a slider movable with the pushing rod, and a hook lever rotatable in conjunction with the slider between a release position in the main body and an engagement position outside the main body. The engagement portion provided on a back surface or inner surface of the cover includes a guide recess to guide an engagement pawl formed on the edge of the hook lever and an engagement part to engage the engagement pawl guided by the guide recess. This cover unit is used in ink-ejecting printers, for example.
In this known cover unit, the cover can be opened accidentally with incidental contact. Additionally, using the hook lever increases the number of components. Although the cover unit can be configured to lock the cover electrically, such a configuration also increases the number of components, and accordingly the size of the unit increases.
Therefore, there is a need for a cover unit capable of preventing the cover from being opened by unintended contact by the user and employing a relatively simple configuration, which known approaches fail to do.